Accompanying progress of downsizing, capacity increase, performance improvement and the like in electronic devices using semiconductors, the heat amount generated from the semiconductors mounted at a high density has been growing. For example, for stable operation of a central processing unit of a personal computer, or a semiconductor device used for regulating a motor of an electric car, a heat sink or a heat dissipation fin is indispensable for heat dissipation, and as a connecting member between a semiconductor device and a heat sink, etc., a material, which can achieve both high insulating properties and thermal conductivity, has been demanded.
In general, as an insulating material used for a printed-circuit board mounting a semiconductor device or the like, organic materials are broadly used. Although such organic materials have highly insulating properties, their thermal conductivity is low and they contribute little to heat dissipation of a semiconductor device or the like. Meanwhile, in some cases, an inorganic material such as an inorganic ceramic is used for heat dissipation of a semiconductor device or the like. Although thermal conductivity of such an inorganic material is high, the insulating properties is not sufficient compared to an organic material, and a material which can achieve both high insulating properties and thermal conductivity has been demanded.
In this connection, various materials, in which an inorganic filler with high thermal conductivity called as a filler is compounded in a resin, have been investigated. For example, an epoxy resin composition, which has a low melt viscosity and is able to compound a filler at a high concentration, has been known (for example, refer to Japanese Patent Application Laid-Open (JP-A) No. 2001-055425). Further, a cured resin composed of a composite system of a general bisphenol A epoxy resin and an alumina filler has been known, which can allegedly attain a thermal conductivity coefficient of 3.8 W/mK by a xenon flash lamp method and 4.5 W/mK by a temperature wave analysis method (for example, refer to JP-A No. 2008-013759). Similarly, a cured resin composed of a composite system of a special epoxy resin, an amine curing agent, and an alumina filler has been known, which can allegedly attain a thermal conductivity coefficient of 9.4 W/mK by a xenon flash lamp method and 10.4 W/mK by a temperature wave analysis method (for example, refer to JP-A No. 2008-013759).
Further, as a cured thermosetting resin superior in thermal conductivity, a cured resin of a thermally conductive resin composition containing boron nitride and polymer ingredients, such as an epoxy resin, an amine curing agent, and a curing catalyst, has been disclosed, which can allegedly attain a thermal conductivity coefficient of from 6 W/mK to 11 W/mK by a temperature wave analysis method (for example, refer to JP-A No. 2008-189818).